Orally administered medicaments are given to patients in many forms such as liquid solutions, emulsions or suspensions or in solid form such as capsules or tablets (as used herein, the term "tablet" means any shaped and compressed solid dosage form, including caplets). Many medicaments require the use of volatile solvents in their preparations, usually organic solvents that may pose health and safety concerns for patients consuming such medicaments and plant personnel producing such medicaments. The volatile solvents are generally undesirable components and/or impurities of the medicament compositions owing to their odor or deleterious effects upon ingestion. Volatile solvents also provide safety risks in production facilities particularly from explosions or inhalation by workers.
It is therefore desirable to provide a carrier system for pharmaceutical actives that does not require the use of organic solvents. Another characteristic desirable for carrier compositions for pharmaceutical actives is good physicochemical stability, i.e., resistance to changes including coalescence, molecular rearrangement, polymorphic changes, and other undesirable physicochemical interactions with pharmaceutical active compositions upon storage and aging.
Many medicaments administered in tablet and capsule form are intended to be swallowed whole. In these situations the often disagreeable taste of the active ingredient need not be taken into account in formulating the medicine, except for the provision of means of preventing the taste from being apparent during the short time that the medicine is in the mouth. Such means may include an appropriately thin and quickly dissolving coating on the tablet, the use of the gelatin capsule form, or simply compressing a tablet firmly enough so that it will not begin to disintegrate during the short time that it is .intended to be in the mouth.
Children, older persons, and many other persons have trouble swallowing whole tablets and even capsules. Consequently, in cases where the dosage to be administered cannot be made into a very small tablet or capsule, it is desirable to provide the medicine in either liquid form or in a chewable solid form. Even when the medicine can be formulated as a liquid, it is desirable also to be able to provide a chewable solid form because it is usually more convenient to carry a supply of tablets than a container of liquid medicine.
A common problem with the chewable tablet form is the often disagreeable taste of the active ingredient which manifests itself during chewing. In some cases, the taste of the active medicament in a tablet can be overpowered by adding flavoring ingredients and/or sugar to the tablets.
There also exist various coating means by which a pharmaceutical active may be shielded by a coating while the tablet is in the mouth but becomes bioavailable later by permeation through the coating or the coating's dissolution in the gastrointestinal tract after the medicament has been swallowed. Examples of such coating systems are described for example in U.S. Pat. No. 4,851,226 which discloses chewable medicament tablets wherein the granules of active ingredient are coated with a blend of cellulose acetate or cellulose acetate butyrate and polyvinyl pyrrolidone (PVP).
The present invention is directed to the discovery of a solventless coating or carrier system which can achieve taste masking of pharmaceutical products which utilizes an edible and physicochemically stable carrier composition. This carrier composition is used to form a "matrix" which is defined herein as a solid composition comprising a carrier and/one or more pharmaceutical actives.